1. Field of the Invention
The present invention relates to, for example, a small-sized vehicle such as a saddle type three-wheel or four-wheel vehicle used for farming, an ATV (All Terrain Vehicle) for sportive traveling off-road, a golf cart, and other small-sized vehicles. More specifically, the present invention relates to a small-sized vehicle having an electric motor-driven power steering apparatus.
2. Description of the Related Art
Generally, a small-sized vehicle used for traveling off-road has the following structure. Front and rear wheels each having a balloon tire with low pressure and wide diameter are disposed at the front and rear of a vehicle body frame, and an engine unit is mounted between the front and rear wheels. Further, a steering shaft is arranged between the left and right front wheels, and a wheel-type steering handle or a bar-type steering handle is attached to the upper end of the steering shaft. A small-sized vehicle of this type can travel off-road at will by turning the steering handle from side to side.
In recent years, some users expect further operational improvements when maneuvering the small-sized vehicle so as to reduce a load on operating the steering handle.
Accordingly, an electric motor-driven power steering apparatus which is connected to a steering shaft to thereby supply the steering shaft with an assisting steering force from the electric motor has been suggested.
When the power steering apparatus is provided, a battery is required to be mounted on the vehicle for supplying the electric motor with a power source. Preferably, the battery is arranged in the vicinity of the electric motor, that is, in the vicinity of the steering shaft. Further, a radiator for cooling engine cooling water using moving air is often provided in front of the steering shaft. In this case, the cooling air that passes through the radiator is applied to the battery depending upon the location of the battery. Meanwhile, the battery generates heat due to chemical reactions in the battery, such that the battery must appropriately emit the heat. However, when the cooling air that passes through the radiator is applied to the battery, the battery is inhibited from emitting the heat. Therefore, problems arise in that the performance and operating life of the battery deteriorate.